The deal for the Oil and Pipelines Agency has the potential to be extended another two years.
Costain said the skills it acquired with the £18.8m acquisition of Promanex last August were instrumental to winning the jon.
Work will involve maintaining and extending the Government’s strategic pipeline network including six Royal Navy oil fuel depots on behalf of the Ministry of Defence.
Andrew Wyllie, Chief Executive of Costain, said: “The award of this contract by a new customer demonstrates the value that Promanex has brought to Costain in providing the full life of asset services in high growth market sectors.
“It also marks an important stage in the ongoing transformation of the Group as we continue to broaden our service offering, both organically and by targeted acquisitions.
“Our strategy of focussing on major customers whose spending plans are driven by national need, regulatory commitments or essential maintenance requirements continues to deliver results.
“We look forward to working with the OPA to ensure the safe, cost effective and efficient operation and maintenance of this strategic national asset.”